This invention relates to a pneumatic timing device and, more particularly, to an intermittent suction regulator for providing various pulsed, timed signals to operate a positive pulse suction device.
Intermittent suction devices are used regularly to remove fluids from patients cavities, such as the stomach, and typically are utilized post-operatively to remove those fluids. Such devices operate typically from a main source of vacuum that is available in hospital recovery rooms by means of central piping systems.
In non-intermittent suction units, the hospital vacuum system withdraws the fluids continuously into some receiver and automatically discontinues the withdrawing cycle only when the collection container is full or hospital personnel disable the system.
With intermittent suction, the continuous withdrawing of fluids is intermittently, at timed intervals discontinued. In some units, the vacuum to the tubing withdrawing the fluids is cycled to atmospheric pressure so that a portion of the fluid moves backwardly toward the patient in order to clear obstructions in the line or to move the catheter away from the wall of the stomach. One difficulty with such systems is that the back flush is carried out to some extent by gravitational forces and therefore the collection container was placed higher than the patient, often incorporated into the timing apparatus itself on the hospital wall at the height of the receptacle providing the vacuum. In addition, gravity force often was not effective in that the tubing carrying fluid from the patient seldom contained a solid line of liquid but more often carried pockets of gas. A typical device of the type that returned the line withdrawing fluids to atmospheric pressure is shown and described in U.S. Pat. No. 3,659,605 of Ulrich Sielaff.
In an effort to correct some of the problems, positive pulse devices have been proposed and which send a positive quantity of fluid previously withdrawn from the patient, backwards toward the patient to clean the passageways. One of such devices is shown and described in U.S. Pat. No. 4,315,506 to Kayser et al.
While the normal suction/atmospheric cycle is sufficient to operate a device such as that of Kayser et al., it is advantageous to use other control systems, that provide more than one vacuum/atmospheric signal to the positive pulse suction device. By having more than one output signal from an intermittent suction regulator, one vacuum signal may be regulated in accordance with the desired vacuum to be applied to the patients cavity while the other vacuum signal may be unaffected by changes in the suction level to the patient and thus can independently control the timing of the positive pulse device. In addition, though the use of a control unit or suction regulator having two (2) output signals, one signal can be delayed or altered with respect to time with reference to the other signal.